When non-relativistic Coulombic electron-electron interactions
are added to the kinetic Hamiltonian (REF ), graphene represents a new type of many-electron problem,
distinct from both an ordinary 2D electron gas (EG) and from quantum electrodynamics.
The Dirac-like wave equation and the chirality of its eigenstates lead indeed to both unusual electron-electron interaction effects [1]}, [2]}, [3]}, [4]}, [5]} and to unusual response
to external potentials [6]}, [7]}.
